Think of rules about interchanging, adding, subtracting rows/columns in a determinant. Then think of easy ways to calculate a determinant.
honestly ive searched through the stickied posts (compilation of proofs) and some other threads, but i think i was just too blind to see it if this was already posted,
anyway, i was told that:
if a row/column of a matrix is a SCALAR MULTIPLE of another (in the same matrix)
then its det is 0,
hmm, i really tried this with some examples and its true,
can anyone prove this? i dont wanna present my answer without any proofs